1. Field of the Invention
The invention relates to a method for manufacturing a semiconductor device, and particularly relates to a method for manufacturing a structure having an air gap.
2. Description of Related Art
Currently, a structure having an air gap in semiconductor devices is developed to prevent electrical interference among the components.
Below, a non-volatile memory device is used as an example for description. In general, the conventional non-volatile memory device is formed of a stacked gate structure including a floating gate and a control gate formed of doped polysilicon. The floating gate is located between the control gate and the substrate and is in a floating state, while the control gate is connected with a word line. In addition, the non-volatile memory device further includes a tunneling dielectric layer and an inter-gate dielectric layer, which are respectively located between the substrate and the floating gate and between the floating gate and the control gate.
Due to the tendency of improving the integration of the devices, the size of the devices is reduced based on a design rule. Under such a circumstance, in order to prevent the increase of a resistor-capacitor (RC) delay and increase of a coupling interference between the floating gates to increase a gate coupling rate, an air gap is formed within the stacked gate structure to solve these issues.
However, as the integration of the device increases, the non-volatile memory device manufactured with the conventional method for manufacturing the non-volatile memory may have a lower air-gap ratio, and are thus unable to effectively reduce the RC delay and solve the issue of coupling interference between the floating gates.